Polymerization of olefins



Patented Sept. 12, 1939 UNITED STATES PATENT OFFICE 2,112,542. POLYMERIZATION or ouzrms No Drawing. Application March 31, 1936,

Serial No. 71,959

18 Claims.

This invention relates to the treatment of hydrocarbons and more particularly refers to the treatment of olefinic hydrocarbons which are normally gaseous at ordinary temperature and pressure.

Olefinic hydrocarbons are generally more chemically active than other classes of hydrocarbons. Hydrocarbons containing a triple bond or more than one double bond between carbon atoms are particularly active. When unsaturated hydrocarbons are subjected to the infiuence of a polymerizing catalyst, they condense and form substances of higher molecular weight. The more active olefinic hydrocarbons are ex tremely sensitive to polymerization catalysts and form hydrocarbons of a higher molecular weight under relatively mild conditions of treatment.

Olefinic hydrocarbons with which the present invention is concerned occur along with corresponding parafiinic or saturated hydrocarbons in commercial hydrocarbon mixtures, such as those encountered in the cracking of petroleum, in gas-making processes and as by-products in various chemical industries. As a result of cracking, olefins are found in large percentages in the fixed gases as well as in the gasoline boiling range fractions. Normally these fixed gases from the cracking processes are utilized as fuel. Only a very small percentage of the gases produced by cracking are subjected to processes for the utilization of the olefinic constituents.

Alcohols such as isopropyl alcohol and others are produced commercially to some extent by first absorbing the olefins in the cracked gases in sulfuric acid and subsequently hydrolyzing the acid esters to produce the desired alcohols.

The present invention provides for more efspecific embodiment pyrosulfates or the salts of pyrosulfuric acid may be used either alone or in admixture with the persulfates. i The present process is particularly directed to the production of dimers and trimers from monoolefins, particularly such olefins whose lower polymers boilat temperatures within the approximate range of commercial motor fuel, say

, for example, from 100 to 400 F. It has been 5 foundthat the dimer-sand some of the trimers of propylene, the butylenes and amylenes boil within this range and furthermore that these compounds have unusually high antiknock characteristics. The following table shows the apl0 proximate boiling points of the dimers of pro-- pylene, butylenes, amylenes and hexylenes which will occur in appreciable quantities in the gases and the lower boiling liquids from oil cracking processes. l5

Boiling points of olefin dimers Hexylene 155 F. Octylene 255 F. Decylene 323 F. 20 Dodecylene a.. 417 F.

The lower boiling and normally gaseous olefins, particularly ethylene, are the more resistant to polymerization. By proper selection of the more active combination of catalysts and by treatment 25 under more drastic conditions, it is found that these relatively inert lower boiling gaseous olefins may also be readily polymerized.

One of the essential ingredients of the catalysts which may be employed in catalyzing olefins ac- 30 cording to the present invention,- are the salts of persulfuric acid (1128208). The most easily formed persulfate is that of ammonia, which is conveniently prepared by the electrolysis of ammonium sulfate in compartment cells, the am moniumpersulfate being continuously formed by anodic oxidation, and the anode solution being continuously replenished by the addition of aminonium. sulfate. The persulfate is a white crystalline solid which has a specific gravity of 1.982.

Other persulfates, such as, for example, those of sodium or potassium, may be prepared by adding their carbonates or hydroxides to concentrated solutions of ammonium persulfate whereupon the persulfates of alkali metals precipitate. These compounds may be employed advantageusly in particular cases either alone or in com.- *bination with the ammonium salt. Persulfates of the following metals are also available: lithium, caesium, rubidium, calcium, magnesium, strontium, thallium, lead, manganese, iron, nickel.

Other catalysts which may be utilized-in polymerizi ng olefins will have as their active constituents salts of pyrosulfuric acid of the formula HzSaO-x. This acid may be considered as a 5:;

compound of one molecule of water and two molecules of sulfur trioxide and as corresponding to a sulfuric acid containing 45% free sulfur trioxide by weight. It is a crystalline solid melting at 35 C. Numerous salts of this acid have been prepared, the most common of which are those of sodium and potassium, which are best prepared by the action of sulfur trioxide upon their anhydrous normal sulfates. Sodium pyrosulfate NazSzOw has a melting point of 400 C., and a density of 2.66. The melting point of the potassium salt is slightly higher being 414 'C., while its density is slightly lower; that is 2.51. In addition to the two simple salts mentioned, the existence of the following double salts has been confirmed:

relatively inert materials.

Catalysts may be prepared by adding water solutions of thesalts of pyrosulfuric or persulfuric acids to a solid absorbent material such as kieselguhr; thoroughly mixing the ingredients and subjecting them to heat at a temperature of approximately 500 F. for the purpose of driving off the excess moisture. Small amounts of carbonizable material, such as starch or agar agar may be added prior to the mixing and heating.

Salts of the pyrosulfuric and per-sulfuric acids may also be added to the spacing agent in solid form and the constituents ground, mixed, and heated.

After heating the catalyst mixture, it is ground and sized. If desired, the catalyst may be shaped in specially desired forms and baked in that state.

A number of different absorbent carrying materials, which vary somewhat in their absorptive capacity, and also in their chemical and physical properties and their influence upon the catalytic effect of the mixture, may be employed. One class comprises materials of predominantly siliceous character and includes diatomaceous earth, kieselguhr and artificially prepared porous silica. Some of the naturally occurring diatoms will contain minor amounts of highly active aluminum oxide which in some instances seems to contribute to the total catalytic effect of the solid catalyst. v

Another class of materials which may be employed either alone or in conjunction with the first class comprises generally certain members of the class of aluminum silicates and includes such naturally occurring substances as various fullers earths and clays, such as bentonite, montmorillonite, etc. The class also includes certain artificially prepared aluminum silicates of which a purified aluminum silicate made by treating certain selected clays with hydrochloric acids or other mineral acids and washing out the reaction products is representative. The naturally occurring substances of this type are characterized by a 'high absorptive capacity and they may also contain traces of active ingredients which assist in producing the desired polymerizing effects.

Again each substance which may be used alternatively will exert its own specific influence, which will not necessarily be identical with that of the other membersof the class.

In some cases the structure of the solid pyrosulfuric or persulfuric catalysts may be improved by the primary incorporation of' minor quantities of organic materials which yield a carbonaceous residue on heating. Substances which may be used in this manner include such materials as cellulose, starches, sugars, glue, gelatin, flour, agar-agar, etc. They evidently function as binders to some extent to prevent the breakdown of the catalyst structure when subjected to elevated temperatures and the action of hydrocarbon gases. The catalyst composite may be used in particle sizes of from approximately 5 to 20 mesh or may be made up into small briquettes.

Owingto the possibility of varying the ingredients which go to form the catalyst masses, a number of alternatives exist, each of which will have its own peculiar catalyzing and polymerizing character, which will not be exactly equivalent to masses of difierent composition.

While treatment of olefinic gaseous hydrocarbons by persulfates and pyrosulfates may be effected in a variety of ways, a few of which will be mentioned as indicating the wide applicability of these compounds. A convenient method of use consists in placing a mass of finely divided catalytic composite granules in a tower or column through which the vapors may pass upwardly or downwardly, preferably the latter. The. melting points of the salts most commonly employed are considerably above the temperature under which treatment is normally carried out in practice. It is within the scope of the invention to employ a number of treating towers in parallel so that olefinic gases may be continuously treated, a tower containing fresh treating reagent being cut in as the others become spent.

. The polymerizing of gaseous olefins with catalysts of the present character may be brought about under numerous combinations of temperature and pressurealthough the best results for any given pure olefin or mixture of olefins, such as those encountered in the gases from oil cracking plants, will usually correspond to a particular set of conditions. It is a feature of the present type of catalyst that treatment may be conducted at temperatures as high as 550". F. and superatmospheric pressures up to several hundred pounds per square inch without danger of over-polymerization resulting in the formation of heavy tar-like polymers instead of liquids of gasoline boiling range.

After the catalysts have been in operation for some length of time, they become fouled by carbon particles depositing ontheir surfaces. The catalysts included in the present classes are readily regenerated after they have been contaminated by surface carbon deposits, merely by burning off the deposits with air or other oxidizing gas at moderate temperature. Following the Example 1 Percent CH4 0.5 C2I-I4 0.7 CzHs 5.6 Cal-In 11.9 C3H 27.8 i-C4H1o 16.4 i-C4Hs 7.9 'n-C4Ha 13.2 nC4H1o 16.0

This polymerization operation produced approximately five gallons of polymer product per thousand cu. ft. of gas mixture treated. From the following table giving the properties of this liquid polymer product it is obvious that a premium gasoline fuel is produced.

A. P. I. gravity 61.8 Gum A. S. T. M. mg/1000 cc 5 Octane number-motor method 81 Vapor pressure lbs/sq. in. Reid 9.0 I. B. P 100 F. 50% over 206 over 372 End point 404 Example 2 In this example, potassium pyrosulfate (&S207) was added in equal parts by weight to kieselguhr and the mixture stirred and heated to approximately 550 F. The baked catalyst was then broken up and sized into small particles.

The catalyst then was subjected to contact with similar gas under the same conditions of temperature and pressure as given in Example 1.

As a result of contact with the catalytic material, a liquid polymer product of approximately 4.5 gallons per thousand cu. ft. of gas mixture treated was produced afi'd had-the following composition.

A. P. I. gravity"; 61.2 Gums A. S. T. M. mg/1000 cc 6 Octane number-motor method 82 Vapor pressure lbs. /sq. in. Reid 8.5 I. B. P 108 F. 50% over 212 95% over 385 End point 410 The foregoing disclosure of the nature of the invention and description of one of its operations will serve to define its scope and indicate to a large extent its value in the art to which it applies. However, since the process is applicable to treatment of any mixture of olefins by pyro" and persulfuric acid salts, and since the apparatus used and the conditions of operation may be varied over a wide range, it is not intended that the foregoing descriptive matter and the examples given be construed as limitations on the broad scope of the invention.

I claim as my invention:

.1. A process for the conversion of normally aseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising a mixture of a salt of pyrosulfuric acid and a solid adsorbent. I

2. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising a salt of pyrosulfuric acid.

3. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising a mixture of an alkali metal salt of pyrosulfuric acid and a solid adsorbent.

4. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising an alkali metal salt of pyrosulfuric acid.

5. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising a mixture of an alkaline earth metal salt of pyrosulfuric acid and a solid adsorbent.

6. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising an alkaline earth metal salt of pyrosulfuric acid.

'7. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising a mixture of a heavy metal salt of pyrosulfuric acid and a solid adsorbent.

8. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising a heavy metal salt of pyrosulfuric acid.

9. A process for the conversion of normally gaseous olefins into liquid olefin'polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising a calcined mixture of a salt of pyrosulfuric acid and a solid adsorbent.

10. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising a calcined mixture of a salt of pyrosulfuricacid and kieselguhr.

11. Aprocess for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising a calcined mixture of a salt of pyrosulfuric acid and a siliceous material.

12. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins,

to the action of a solid catalyst comprising a calcined mixture of a salt of pyrosulfuric acid and a solid adsorbent and an organic material which yields a carbonaceous residue on heating.

13. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising a mixture of a salt of pyrosulfuric acid and a solid adsorbent containing aluminum oxide.

14. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins, to the action of a solid catalyst comprising a calcined and briquetted mixture of a salt of pyrosulfuric acid and a solid adsorbent.

15. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas, at a temperature adequate to polymerize said olefins,

to the action of a solid catalyst comprising a mixture of salts of persulfuric and pyrosulfuric acids and a solid adsorbent.

16. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas at a temperature adequate to polymerize said olefins to the action of a solid catalyst comprising a calcined mixture of salts of persulfuric and pyrosulfuric acids and a solid adsorbent.

17. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas at a temperature adequate to polymerize said olefins to the action of a solid catalyst comprising a calcined mixture of salts of persulfuric and pyrosulfuric acids and kieselguhr.

18. A process for the conversion of normally gaseous olefins into liquid olefin polymers, which comprises subjecting olefin-containing gas at a temperature adequate to polymerize said olefins to the action of a solid catalyst comprising a calcined mixture of salts of persulfuric and pyrosulfuricacids and a solid adsorbent and organic material which yields a. carbonaceous residue on heating. 7 i

JACQUE C. MORRELL. 

